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*DIFFUSIVITY
Specify mass diffusivity.

This option is used to define the mass diffusivity of a material diffusing through a base material. It must be used in conjunction with the *SOLUBILITY option.

Products: Abaqus/Standard  Abaqus/CAE  

Type: Model data

Level: Model  

Abaqus/CAE: Property module

References:

Optional parameters:

DEPENDENCIES

Set this parameter equal to the number of field variables included in the definition of diffusivity. If this parameter is omitted, the diffusivity is assumed not to depend on any field variables but may still depend on concentration and temperature. See “Specifying field variable dependence” in “Material data definition,” Section 21.1.2 of the Abaqus Analysis User's Guide, for more information.

LAW

Set LAW=GENERAL (default) to choose general mass diffusion behavior. Set LAW=FICK to choose Fick's diffusion law. LAW=FICK and the *KAPPA, TYPE=TEMP option are mutually exclusive.

TYPE

Set TYPE=ISO (default) to define isotropic diffusivity. Set TYPE=ORTHO to define orthotropic diffusivity. Set TYPE=ANISO to define fully anisotropic diffusivity.

Data lines to define isotropic diffusivity (TYPE=ISO): 

First line:

  1. Diffusivity, D. (Units of L2T–1.)

  2. Concentration, c.

  3. Temperature, .

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five):

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the diffusivity as a function of concentration, temperature, and other predefined field variables.

Data lines to define orthotropic diffusivity (TYPE=ORTHO): 

First line:

  1. . (Units of L2T–1.)

  2. .

  3. .

  4. Concentration, c.

  5. Temperature, .

  6. First field variable.

  7. Second field variable.

  8. Third field variable

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than three):

  1. Fourth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the diffusivity as a function of concentration, temperature, and other predefined field variables.

Data lines to define anisotropic diffusivity (TYPE=ANISO): 

First line:

  1. . (Units of L2T–1.)

  2. .

  3. .

  4. .

  5. .

  6. .

  7. Concentration, c.

  8. Temperature, .

Subsequent lines (only needed if the DEPENDENCIES parameter is used):

  1. First field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the diffusivity as a function of concentration, temperature, and other predefined field variables.